Alta California

Alta California was a province of New Spain and a department of Mexico, with Monterey serving as its capital. Along with Baja California, it split from Las Californias in 1804, and it became a territory of Mexico in April 1822 before being renamed to "Alta California" in 1824. The province included all of California, Nevada, and Utah and parts of Arizona, Wyoming, New Mexico, and Colorado. The Spanish and Mexicans never colonized north of the Sonoma area, leaving interior areas such as much of the Central Valley and the deserts of California in the de facto possession of the Native American tribes. In addition, large areas east of the Sierra Nevada and the San Gabriel Mountains were never colonized. During the Mexican-American War, the United States acquired Alta California from Mexico, formally acquiring the region under the Treaty of Guadalupe Hidalgo in 1848. The Mexican Cession was then partitioned into several US territories.